The Supreme Court’s Rule Against Functional Claiming, and the Federal Circuit’s Failure to Recognize It– A Deep Dive into its Origin and Continuing Vitality

The Long-Standing Statutory Requirement for “Particularly Pointing Out” the Invention

The patent act of 1836 created the U.S. requirement for patent claims, and stated that an applicant must “particularly specify and point out the part, improvement, or combination, which he claims as his own invention or discovery. Act of July 4, 1836, ch. 357, § 6, 5 Stat. 117, 119. Likewise, the 1870 patent act said the applicant “shall particularly point out and distinctly claim the part, improvement, or combination which he claims as his invention or discovery.” Act of July 8, 1870, ch. 230, § 26, 16 Stat. 198, 201 (codified in Rev. Stat. § 4888, 18 Stat. 954). This language was essentially repeated in the 1952 patent act, and stands today as “[t]he specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. 35 U.S.C. § 112(b) (2011). The Supreme Court has noted that the “1952 Patent Act is not materially different from the 1870 Act with regard to claiming, reissue, and the role of the PTO (Warner-Jenkinson Co. v. Hilton Davis Chem. Co., 520 U.S. 17, 26 (1997)), and that in reenacting statutory language that the Supreme Court has construed, “Congress must be considered to have adopted also the construction given by this Court to such language, and made it a part of the enactment.” Helsinn Healthcare, S.A. v. Teva Pharms. USA, Inc., 139 S. Ct. 628, 634 (2019) (quotations omitted).

Functional claiming under the 1836 Patent Act

The Supreme Court first addressed the particularity requirement with respect to claim 8 of Samuel Morse’s telegraph patent, which recited “the motive power is the electric or galvanic current, and the result is the marking or printing intelligible characters, signs, or letters at a distance.” The Court held that “He can lawfully claim only what he has invented and described, and if he claims more his patent is void.” O’Reilly v. Morse, 56 U.S. (15 How.) 62, 121 (1854).

Later that same year, in assessing a patent for “Rolling Puddler’s Balls,” an iron manufacturing component, the Court stated that “it is for the discovery or invention of some practicable method or means of producing a beneficial result or effect, that a patent is granted, and not for the result or effect itself[.]. . . . He cannot describe a machine which will perform a certain function, and then claim the function itself, and all other machines that may be invented to perform the same function.” Corning v. Burden, 56 U.S. (15 How.) 252, 268-269 (1854).

And a few years later, in analyzing a patent for “Machinery for making Hat Bodies,” the Court warned that “[w]e find here no authority to grant a patent for a ‘principle’ or a ‘mode of operation’[.]” Burr v. Duryee, 68 U.S. (1 Wall.) 531 (1864).

Functional claiming under the 1870 Patent Act

In the late 19th Century, the Supreme Court invalidation of purely functional claims continued under the 1870 patent act.  In Fuller v. Yentzer, the Court addressed a “Sewing Machine Guide” patent that recited “forming one, two, or more creases in cloth by means of markers on opposite sides of the cloth[.]” The Court held that “[p]atents for a machine will not be sustained if the claim is for a result, the established rule being that the invention, if any, within the meaning of the Patent Act, consists in the means or apparatus by which the result is obtained, and not merely in the mode of operation, independent of the mechanical devices employed.” 94 U.S. 288, 290 (1877).

In two cases from the 1890s, the Court made clear that its previous precedents established a rule against functional claiming. “[A] valid patent cannot be obtained for a process which involves nothing more than the operation of a piece of mechanism, or, in other words, for the function of a machine[.]” Risdon Iron & Locomotive Works v. Medart, 158 U.S. 68 (1895) (analyzing a patent for “Manufacture of Belt Pulleys”). Likewise, in considering a patent for a railroad car’s “Fluid Pressure Brake Mechanism,” the Court stated that “a claim for the function … is open to the objection, held in several cases to be fatal, that the mere function of a machine cannot be patented. … the alleged infringer … must have reached [the same result] by substantially the same or similar means, or the rule that the function of a machine cannot be patented is of no practical value.” Westinghouse v. Boyden Power Brake Co., 170 U.S. 537 (1898)

This trend continued right up to the Second World War.  Where a patentee argued that its claim covered any “starchy carbohydrate” — whether or not it was prepared by the process described in the patent — the Court held “that the patentee may not by claiming a patent on the result or function of a machine extend his patent to devices or mechanisms not described in the patent is well understood. . . . [T]he attempt to broaden product claims by describing the product exclusively in terms of its use or function is subject to the same vice as is the attempt to describe a patentable device or machine in terms of its function. Holland Furniture Co. v. Perkins Glue Co., 277 U.S. 245 (1928). Ten years later, where a patent recited a lamp filament having “grains of such size and contour as to prevent substantial sagging,” the Court held that the claim fell “within the condemnation of the doctrine that a patentee may not broaden his product claims by describing the product in terms of function.” General Electric Co. v. Wabash Appliance Corp., 304 U.S. 364, 370 (1938).  And in what is perhaps the strongest statement of the Supreme Court’s functional claiming prohibition, a patent for “Carbon Black and Process of Making Same” claiming “aggregates having a spongy porous interior” was held to “fall afoul of the rule that a patentee may not broaden his claims by describing the product in terms of function.” United Carbon Co. v. Binney & Smith Co., 317 U.S. 228, 234 (1942).

Congress creates a safe harbor for means-plus-function claiming

When faced with a patent directed to “Means for Measuring the Location of Obstructions in Wells” requiring “means … for tuning … to the frequency of echoes from the tubing collars,” the Court held that “The language of the claim ... describes this ... element in the ‘new' combination in terms of what it will do rather than in terms of its own physical characteristics or its arrangement in the new combination apparatus. We have held that a claim with such a description of a product is invalid.” Halliburton Oil Well Cementing Co. v. Walker, 329 U.S. 1, 8 (1946) (“Halliburton Oil”).

Six years later, Congress specifically authorized the claim format at issue in Halliburton Oil, providing a new section to 35 U.S.C. § 112: “An element in a claim for a combination may be expressed as
a means or step for performing a specified function, without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.”35 U.S.C. § 112 ¶ 3 (now ¶ 6) (1952); 35 U.S.C. § 112(f) (2011).

The rule against functional claiming – as (not) interpreted by the Federal Circuit

The Supreme Court has not yet had the opportunity to consider the interplay between its statute-based rule against functional claiming and the 1952 Act’s statutory authorization for means-plus-function claiming. However, in holding that claim construction is a matter for courts rather than juries, the Court noted that “A claim covers and secures a process, a machine, a manufacture, a composition of matter, or a design, but never the function or result of either[.].” Markman v. Westview Instruments, Inc., 517 U.S. 370, 373 (1996) (internal quotations omitted).

The Federal Circuit’s creation in 1982 promised to bring a new era of uniformity to patent law. In doing so, however, that court has viewed the authorization for means-plus-function claiming as leaving the overarching rule against functional claiming on the cutting-room floor.  For example, in Valmont Indus., Inc. v. Reinke Mfg. Co. the court took the position that in “Halliburton [Oil], the Supreme Court prohibited use of means-plus-function language to describe the ‘most crucial element’ of a combination claim[.] … Congress decided to permit broad means-plus-function language, but provided a standard to make the broad claim language more definite. … With this new section, the 1952 Act rendered Halliburton [Oil] obsolete.” 983 F.2d 1039, 1042 (Fed. Cir. 1993) (citations omitted) (emphasis added); see also Greenberg v. Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1582 (Fed. Cir. 1996) (“Congress enacted paragraph six … to overrule that holding.”).

Entering the new millenium, the Federal Circuit took an increasingly charitable view of functional claims, opining that “[a]lthough our predecessor court later recognized that ‘there is nothing intrinsically wrong with’ using functional language in claims, it noted that in some instances, use of functional language can fail ‘to provide a clear-cut indication of the scope of subject matter embraced by the claim’ and thus can be indefinite. . . .  When a claim limitation is defined in purely functional terms, the task of determining whether that limitation is sufficiently definite is a difficult one that is highly dependent on context.” Halliburton Energy Services, Inc. v. MI LLC, 514 F. 3d 1244, 1255 (Fed. Cir. 2008) (quoting In re Swinehart, 439 F. 2d 210, 212-13 (C.C.P.A. 1971) (emphasis added).

But at least some members of the Federal Circuit appeared to recognize that the Supreme Court’s rule against functional claiming still has vitality.  In his concurring opinion in Williamson v. Citrix Online, LLC, Judge Jimmie Reyna posited that “[a]rguably, th[e] rationale [of the Supreme Court in Halliburton [Oil] applies to functional claiming generally, not just to claims that recite ‘means.’ Indeed, the Halliburton [Oil] Court relied on precedent invalidating functional claims that did not recite the term "means." … The continued viability of this rationale, and its impact on how this Court applies § 112, para. 6 merits attention.” 792 F. 3d 1339, 1347 (Fed. Cir. 2015) (en banc); see also id. at 1363 (“Paragraph 6 is a statute of authorization and limitation; it does not annul the other provisions of the statute.”) (Newman, J. dissenting). It is nearly a decade since the Federal Circuit has made any reference to Halliburton Oil and the Supreme Court’s rule against functional claiming, and then only in passing. See Amdocs (Israel) Ltd. v. Openet Telecom, Inc., 841 F. 3d 1288, 1295 (Fed. Cir. 2016) (“We note that, though not in terms of ‘abstract idea’ but rather adequacy of definition, years ago the Supreme Court outlawed such broad ‘ends’ or function claiming as inconsistent with the purposes of the Patent Statute. Congress, however, a few years later softened the rule [to permit means-plus-function claiming].”).

More recently, however, the Federal Circuit has analyzed whether functional claims meet the statutory “definite structure” requirement without any citation or analysis of the Supreme Court’s prohibition of functional claiming. See Dyfan, LLC v. Target Corp., 28 F. 4th 1360 (Fed. Cir. 2022) (“In determining whether software limitations like those at issue here recite sufficient structure, we can look beyond the initial ‘code’ or ‘application’ term to the functional language to see if a person of ordinary skill would have understood the claim limitation as a whole to connote sufficiently definite structure.”); see also WSOU Investments LLC v. Google LLC, 2023 WL 6889033, **2-6 (Fed. Cir. Oct. 19, 2023) (“This is the epitome of functional claiming: a black box that captures any and all structures that fulfill the function[.]”)

Using the Supreme Court’s Rule against functional claiming to invalidate software claims

I had the privilege of representing Squarespace Inc. against a pair of cases brought by patent assertion entities affiliated with the IP Investment Group in the Delaware district court. In that case, Squarespace moved to dismiss all asserted patent claims as invalid based on the Supreme Court rule against functional claiming.  The patentee argued that the Halliburton Oil and all previous cases had been overruled, based on the Federal Circuit’s statements in Valmont and Greenberg. Judge Stark, since elevated to the Federal Circuit, denied the motion as premature because “I need to get to claim construction before I could properly address the legal issue[.]” DataCloud Techs., LLC v. Squarespace, Inc., No. 21-164-LPS, 2022 U.S. Dist. LEXIS 18810 (D. Del. Feb. 2, 2022). The cases settled as the parties engaged in claim construction briefing.

Last year, the Supreme Court addressed the parallel statutory enablement requirement of 35 U.S.C. § 112(a); the High Tech Inventors Alliance and the Computer & Communications Industry Association submitted an amicus brief inviting the Court to invalidate the claims as invalid under the Court’s rule against functional claiming: “[The claims at issue] are naked functional claims … [t]hey claim not what the invention is, but only what it does. And so … they are invalid … based on an unbroken chain of this Court’s precedents … including Morse, Holland Furniture, General Electric, and Halliburton Oil. … Section 112(f) acts as a limited safe harbor against invalidation of naked functional claims.” In rendering its opinion, the Court’s opinion relied on Morse, Holland Furniture, and other early cases for their enablement holdings, however, the Court did not mention its rule against functional claiming. Amgen Inc. v. Sanofi,143 S. Ct. 1243, 1252-1254 (2023).

The Supreme Court’s continued reliance on its older case law makes clear that a company charged with infringement of purely functional patent claims should seriously consider defending itself with the Supreme Court’s rule against functional claiming. As these claims are particularly common in software and computer-implemented inventions, it seems only a matter of time that a case will makes it way to the Federal Circuit – which will have to choose between its own precedent and the Supreme Court’s controlling law.